Patent GB-416664-A (GB)
Title: Process for sensitizing photographic silver halide emulsions
IPC: G03C1/12
Filed: 1933-01-19
Abstract: For sensitizing silver halide emulsions there are employed symmetrical dyes of the formula <FORM:0416664/IV/1> or symmetrical or unsymmetrical dyes corresponding with the formula <FORM:0416664/IV/2> wherein X and Y stand for sulphur or selenium, R stands for hydrogen, alkyl or halogen, and n for 1 or 2, and wherein the benzene nuclei A and B may be substituted or unsubstituted, or salts of such dyes. The benzene rings A and B may contain halogen, alkyl, alkoxy, sulphalkyl or amino groups and may also be replaced by the nuclei of condensed ring systems such as naphthalene, anthracene, acenaphthene, diphenyloxide, or carbazole nuclei.  Those dyes containing an unsubstituted monomethine linkage are prepared by condensing 3-oxythionaphthene or 3-oxyselenonaphthene with chloroform and sodium ethylate or with orthoformic esters and a basic condensing agent such as sodium ethylate (Specification 418,561).  By condensing the foregoing materials with a tetrahalogenmethane or orthoacetic, orthopropionic &c. esters, dyes of the second formula wherein R stands for halogen and alkyl respectively are obtained. Alternatively 3-oxythionaphthene or 3-oxyselenonaphthene may be condensed with an aldehyde of the formula <FORM:0416664/IV/3> (X stands for sulphur or selenium) in presence of sodium ethylate or hydrogen chloride in acetic acid whereby unsymmetrical dyes may also be obtained.  Dyes of the first formula wherein n is 1 are prepared by condensing 3-oxythionaphthene or 3-oxyselenonaphthene with b -ethoxyacroleinacetal, and those wherein n is 2 are prepared by condensing the foregoing materials with a salt of a -phenylamino-e -phenylamino - a  :g  - pentadiene.  The following preparations of dyes are described: (1) 3-oxythionaphthene and 3-oxyselenonaphthene are condensed with chloroform in presence of sodium ethylate; (2) 3-oxythionaphthene and 5 . 6 - benzo - 7 - chloro - 3 - oxythionaphthene (prepared by known methods from 1 - chloro - 2 - amino - 3 - naphthoic acid) are condensed with ethylorthoacetate in presence of sodium ethylate; (3) 3-oxyselenonaphthene is condensed with 2 - formyl - 3 - oxy - 4 - methyl - 6 - chlorthionaphthene in presence of sodium ethylate; (4) 3-oxythionaphthene is condensed with carbon tetrachloride in presence of sodium ethylate; (5) 3-oxythionaphthene is condensed with b  - ethoxyacroleinacetal in pyridine and in presence of piperidine; (6) 3-oxythionaphthene and 3-acetyloxyselenonaphthene are condensed with b -phenylamino-e -phenylamino-a  : \su-pentadiene hydrobromide in alcohol and in presence of diethylamine; (7) 5 - chloro - 3 - oxythionaphthene and dianilidopropene hydrochloride are condensed together in alcoholic sodium methylate solution. British Specification 396,011 and German Specifications 224,567, 239,093, and 240,118 are referred to as comprising processes suitable for the preparation of analogous heterocyclic bodies attached to polynuclear ring systems which may serve as starting materials for the dyes.  The Specification as open to inspection under Sect. 91 relates also to the manufacture of dyes which are assigned the general formula <FORM:0416664/IV/4> wherein X, Y, Z and W stand for oxygen, sulphur or selenium, R for hydrogen, alkyl, alkoxy or halogen, and A or B are defined as above.  Specified processes comprise condensing 2 mols. of a compound of formul <FORM:0416664/IV/5> wherein X and W are as above and R<1> corresponds to the residues A and B above with one mol. of a tetrahalogenmethane or an orthocarboxylic acid or orthocarbonic acid ester in presence of a basic condensing agent; condensing one mol. of a compound of formul <FORM:0416664/IV/6> with one mol. of a compound of formul <FORM:0416664/IV/7> wherein R, X, Y, Z and W are as above and R<1> and R<2> correspond to the residues A and B above.  The use of coumaranone is specified as a starting material in the foregoing processes. This subject-matter does not appear in the Specification as accepted.